Method of making elastic fabrics



March 13, 1956\ B. D. HUBBARD ETAL 2,737,701

METHOD OF MAKING ELASTIC FABRICS Hummm M 1 Mix t mia m www Wj w m I? m Ma 2 i M ya B .Q 1 l 8, m N. Ummm Mam!! 13, 1956 B. D. HUBBARD Erm. 2,737,701

METHOD OF' MAKING ELASTIC FABRICS 2 Sheets-Sheet 2 Filed June 28, 1951 ATTORNEY United States Patent METHOD OF MAKING ELASTIC FABRICS Barton D. Hubbard, Tuckahoe, N. Y., and Paul Dereniuk, Woonsocket, R. I., assignors to United States Rubber Company, New York, N. Y., a corporation of New Jersey Application June 28, 1951, Serial No. 234,034

3 Claims. (Cl. 28-74) This invention relates to a method of making elastic fabrics and more particularly to a method of destroying or rendering inactive the fine heat-shrinkable resinous filaments employed in the fabric to condense the fabric and hold it condensed until an elastic rubber backing is applied thereto.

The Foster Patent No. 2,450,948 for a Methodof Making Elastic Fabrics describes and claims a novel method of making a two-way stretch fabric that has a long stretch in both directions. The fabric of this patent comprises a textile fabric which is contracted both longitudinally and transversely by heat shrunken filaments embodied in the warp and weft, and while the fabric is held contracted by these heat shrunken filaments, it is provided with an elastic backing such as a film of rubber that is adapted to yieldingly hold the fabric in its contraeted condition. It is necessary, in order that this fabric may stretch, to destroy or render inactive the heat shrunken filaments that tend to hold the fabric locked in its contracted condition. If these heat shrunken filaments have a relatively low melting point so that they may be melted or rendered inactive by heat treating the fabric, at a temperature which is not high enough to injure the elastic fabric, then it is a simple matter to destroy such filaments or render them inactive by heating the'fabric, as contemplated by the Foster patent. It is found however that such heat treatment may cause the melted resin of the shrunken filaments to form hard objectionable particles at a face of the fabric.

If the heat shrinkable filaments used to contract the fabric have a relatively high melting point, then it may not be practical to destroy or render these filaments inactive by the application of heat alone, and in this case the-problem of disposing of such shrunken resinous filaments may be more difficult.

The present invention is directed primarily to the problem of destroying or rendering inactive heat shrinkable filaments, when because of their relatively high melting point, heat alone will not destroy or render such filaments `fabric is stretched in the direction in which the heat shrunken filaments extend and is held stretched while it is heated to a temperature considerably above the boiling point of water, the filaments will try to shrink at this elevated temperature and if they are prevented from shrinking by the tension upon the fabric they will break into short lengths between the points where they are *,v locked in the fabric by the weave. This breaking of the filaments into very short lengths renders them inactive so that they no longer interfere with the stretching of Flice condition. Therefore in most cases the filaments should Y be destroyed as herein contemplated.

If the fabric which is to be treated in accordance with the method of the present invention has the heat shrunken filaments therein as weft only, then the fabric need be stretched only weftwise while it is being heated to destroy the filaments. If the heat shrinkable filaments are employed in the warp only, then the fabric needs to be stretched only warpwise while heated to destroy such filament. If the heat shrinkable filaments have been employed in both the warp and weft to produce a twoway stretch fabric then, in order to destroy these filaments, it may be desirable to stretch the fabric longitudinally at an elevated temperature to destroy the longitudinally extending filaments, and then transversely at an elevated temperature to destroy the transversely extending filaments. This stretching of the fabric in two directions for a two-way stretch fabric as just described, however, is not always necessary. Because it is found that if the fabric is stretched transversely while it is prevented from contracting longitudinally, in the presence of heat, both the longitudinally and transversely extend ing filaments will be broken into short lengths by this combined action of heat and tension, provided the fabric being treated has a relatively close firm weave that grips the filaments at numerous short intervals to hold them and cause them to break into short lengths when they are prevented from shrinking under the action of the heat.

The above and other features of the method of the present invention will be further understood from the following description when read in connection with the accompanying drawing, wherein:

Fig. 1 is a top plan view of a small piece of two-way stretch fabric shown after it has been subjected to the filament destroying action of the present invention;

Fig. 2 is a longitudinal sectional view of apparatus for stretching a traveling fabric longitudinally in the presence of heat; l

Fig. 3 is a top plan view with apparatus of Fig. 2;

Fig. 4 is a side view with parts in section of apparatus for stretching a traveling fabric transversely by tentering mechanism in the presence of heat; and

Fig. 5 is a top plan view with parts in section of the apparatus shown in Fig. 4.

The elastic fabric shown in Fig. l of the drawing is the end product which may result from the lmethod of the present invention, and corresponds to the two-way stretch fabric shown in Fig. 5 of the above mentioned Foster patent. This two-way stretch elastic fabric here shown in Fig. l is designated in its entirety by the numeral 10 and comprises a woven or knitted fabric 11 which after it has been shrunken or condensed by the use of heat shrinkable filaments has a rubber backing 12 firmly secured thereto.

'Phe woven or knitted fabric 11 has the desired heat shrinkable properties Iimparted thereto by introducing therein as Warp or weft, or as both warp and weft, a small percent by weight of heat shrinkable resinous filaments such 'for example as described in the above mentioned Poster patent. If desired such heat shrinkable filaments may be cut or broken into short lengths to form what are known as staple filaments which are mixed with parts in section of the rtQn-shrinkable. fibers.. or filaments. such for. example as. cotton fibers, to `thereby form yarn having a small percent of heat shrinkable cut filaments intermixed with a much larger percent of non-.shrinkable fibers. or filaments. Yarns formed of'- these intermixcd fibers, m ay be introduced into the fabric 1l aswarp or weft or as; both warp and weft. The fabric constructed as. just described may be shrunken about one-half its previous `length and width by simply dipping it momentarily in boiling water so that the heat shrinkable filaments will contract the fabric in 'both directions and hold it contracted. ri`his contracted fabric such as indicated by 11 in the drawing may then have a coating of solvent rubber or latex applied to one face thereof as lindicated by 12, so that when this coating is heat cured or vulcanized it will impart good elastic properties to the fabric 1l.

However before this rubber backed fabric will stretch either longitudinally or transverselyy the heat shrunken filaments must be destroyed or rendered inactive. This i-s done in accordance with the present invention in a manner which will now be described.

Referring to Figs. 2 and 3 ofthe drawing, a fabric roll 13 is made of the preformed, shrunken, rubber-backed fabric which is non-stretchable due to `the presence of the heat shrunken fiiaments therein. The longitudinally extending heat shrunken filaments in this fabric are destroyed or broken into very short lengths by treating the fabric upon the apparatus shown in Figs. 2 and 3.

The roll of fabric 13 to be treated is wound on a supporting shaft i4 md ends of this shaft are rotatably supported by the upright bearing members 1d. The fabric supplied by the roll i3 which is indicated by 1 0' before the heat shrunken filaments therein are destroyed and by 1) after these filaments are destroyed, is drawn forward from the supply roll 1:3 by the power driven roll 16 about which the fabric is looped. The rotation of the roll 1'3 is preferably resisted 'by brake means, not shown. The fabric 1d' is held in non-slipping relation lwith the surface of the roll 16 by the idler rolls 17 and 1E. These three rolls are rotatably supported by the upright frame 19. The fabric i6' passes from the idler roll 18 through an opening in the heated'` oven or casing 20. lt then passes under 4an idler roll 2l and about the large steam heated drum or cylinder 22 within this oven and which rotates upon the supporting shaft 23. The oven 20 may receive heat from the drum 22 or it may be independently heated as desired. After the fabric has passed more than half way around this steam heated drum, it passes under an idler roll 24 and then out of the oven through a slotted opening 25, to thev fabric advancing means comprising the power driven roller 26. The fabric is looped about this roll and it is retained in non-slipping engagement therewith by the idler rollers 27 and ZS. These three rollers 2n, 27 and 28 arc rotatably supportedv by the frame 29.

The fabric advancing roll i6 is driven at a predetermined speed, determined by the rate at which it is desired` to pass the fabric through. the oven 29. The driving means may be the sprocket wheel 3d. The fabric advancing roll 26 is driven at a definite ratio but at a higher speed than the roll 16 by the sprocket 31. rfhis difference inV the speed of the two rolls i6 and 26 determines thev amount the fabric is stretched and held stretched while it is subjected to the elevated temperature within the oven 2li. rfhis stretching `of the fabric, which may 'be to the limit permitted by the weave of the fabric, reduces the width of the fabric between the roll 16 and 25. This is shown in Fi 3- where it will be secu `that the width of the fabric is reduced a substantial amount as it passes from the roll id downwardly about the idler roil 1S. and the fabric remains at this reduced width as long as it is subjected to the high longitudinal tension produced by the higher speed of the roll 26 than that of the roll i6. This tension is released as the, fabric passes from the driven roll 26 downwardly about the idler roll 28,

and assuch tension is reduced the fabric spreads laterally as shown in Fig. 3.

The purpose of the treatment illustrated in Figs. 2 and 3 of the drawing is to destroy or render inactive the heat shrunken filaments that extend warpwise of the fabric 10. These filaments are destroyed or broken into very short lengths by stretching the fabric 10 longitudinally to approximately the limit permitted by the weave of the fabric and while the fabric is held so stretched it is subjected to a relatively high temperature. This temperature will cause the heat shrinkable filaments. to try to contract, or shrink, but since the high tension on the fabric preyents such longitudinal shrinkage, these filaments, it is found will break into short lengths under the combined action of the tension and heat. The manner in which these filaments break into short lengths will depend largely upon the firmness and closeness of the weave of the fabric, whereby the filaments are locked, in the fabric at close intervals. v

The temperature required. to Cause the filaments to break up into short lengths. as lust described will depend in part upon the nature., of. the. heat-shrinkable filaments employed in the fabric and upon the speed` at which the fabricis passed through the oven 2t).

A number of. heat-sbunlsa'ble filaments now on the ket may be employed to shrink the fabric 10 as herein contemplated. Such heat-shrinkable filaments are orienred synthetic resiuous filaments whichpcssess. the property know as elastic memory. This property is irnparted to. such filaments by stretching them during the course. of manufacture and then .annealing them by the application of lheat and tension so that they will remain inthev stretched condition until they are again heated. Such filaments areprcferably formed largelyV of polyvinyl chloride. Filaments of this type which are now on the market and which may be employed to shrink the fabric 1f?" are. sold under the names of polystyrene, Vinyon H. S. T. Rhovyl, Fibravyl, and Vinyon NOZZ. rlfhe temperature used to shrink the filaments just mentioned should be approximately 325 F. for an exposure, of 45 seconds, and.v about 275 F. for an exposure of about 5 minutes.

After the fabric 19 has been treated on the apparatus of Figs. 2 and 3. as just described to break up the longitudinally extending heat shrunken filaments, the transversely extending heat shrunken filaments may be broken into short lengths by advancing the fabric 10" as it leaves the apparatus of Fig. 2 to the tenteriug apparatus shown in- Figs. 4 and 5, to subject the fabric to the combined action of heat and lateral tension. The lines X-X of Figs. 2 and 4 showwhere the fabric. ifi' is cut between the two machines. The fabric 10 is shown as passing drectly from the idler roll 28 of Fig. 2 to the idler roll 32 of Fig. 4, which roll serves to force the fabric into engagement with the pins 33 of the tentering chains 34 disposed at each side of the machine where they engage the sprockets 35 as shown in Fig. 5. As the upper runs of these chains travel in a right hand direction they are guided away from each other by the guide rails 56' as is usual in tentering machines, to thereby stretch the fabric 10 transversely to the approximate limit permitted by the Weave of the fabric. If the fabric 1d is passed directly from the oven 20 of Fig. 2 to the tentering mechanism of Fig. 4, itmay be sufficiently hot to render the transversely extending filaments comparatively easy to stretch, but it may be desirable to further elevate the temperature of this fabric before it is stretched transversely. This is done by causing the upper run o f the tentering machine to pass through the hot box or oven 37, which is constructed, as will bey apparent from Fig. 5, to heat the fabric before the tentering chains start to, diverge away from each other. This oven will keep the fabric hot while it travels a substantial distance after it has been fully stretched transversely, so that this high tension and temperature will, serve to break the transversely extending heat shrinkable filaments into short lengths. As the fabric 10 passes out of the oven 37 it will have a substantial stretch both longitudinally and transversely due to the fact that it is now free from the holding action of the transversely and longitudinally extending heat shrunken filaments. The tentering mechanism may be supported by the uprights 38.

In dealing with certain fabrics it is desirable to subject them to the successive treatments above described by passing the fabric first through the apparatus shown in Figs. 2 and 3 and then through the apparatus shown in Figs. 4 and it is found, however, that in certain closely woven fabrics where the heat shrunken filaments are firmly bound in the fabric at short intervals, the widthwise stretching of the fabric in the presence of heat as illustrated in Figs. 4 and 5 of the drawing, serves to destroy or break up into short lengths the transversely extending filaments and also the longitudinally extending filaments. This is due to the fact that the tentering machine prevents the fabric from contracting transversely, and also prevents it from contracting longitudinally. This prevents the filaments from contracting under the high temperature; with the result that the treatment illustrated in Figs. 4 and 5 may render inactive both the longitudinally and transversely eX- tending filaments, to thereby provide the two-way stretch fabric shown in Fig. l of the drawing.

Having thus described our invention, what we claim and desire to protect by Letters Patent is:

1. The method of making an elastic fabric which comprises, weaving a fabric of textile yarns having a small percent of heat-shrinkable filaments sufcient to shrink the fabric a substantial amount in the fabric in the direction it is to stretch and which will shrink a substantial amount if free of tension when heated, heating the fabric to the filament shrinkage temperature to contract the fabric and hold it contracted, coating the contracted fabric with rubber, curing the rubber, and then breaking said filaments into suiciently short lengths to release the contracted fabric by heating the fabric to the filament shrinking temperature and while at this temperature stretching the fabric to cause the heated and stretched laments to break under the combined action of the heat and tension.

2. The method of making a woven two-way stretch elastic fabric which comprises, weaving a fabric of textile yarns having a small percent of heat-shrinkable filaments suicient to shrink the fabric a substantial amount in the warp and weft and which will shrink a substantial amount if free of tension when heated, heating the fabric to the filament shrinking temperature to contract the fabric and hold it contracted, coating the contracted fabric with rubber, curing the rubber, and then breaking said filaments into sufficiently short lengths to release the contracted fabric by heating the fabric to the filament shrinking temperature and while at this temperature stretching the fabric to cause the heated and stretched filaments to break under the combined action of the heat and tension.

3. The method of making a woven two-way stretch elastic fabric which comprises, weaving a fabric of textile yarns having a small percent of heat-shrinkable filaments sufficient to shrink the fabric a substantial amount in the warp and weft and which will shrink a substantial amount if free of tension when heated, heating the fabric to the filament shrinking temperature to contract the fabric and hold it contracted, coating the contracted fabric with rubber, curing the rubber, and then breaking said filaments into sufficiently short lengths to release the contracted fabric, said breaking being effected by heating the fabric to a temperature near but below the filament melting temperature and while at this temperature stretching the fabric to cause the stretched filaments to break under the combined action of the heat and tension.

References Cited in the file of this patent UNITED STATES PATENTS 2,262,861 Rugeley Nov. 18, 1941 2,278,895 Rugeley Apr. 7, 1942 2,278,896 Rugeley Apr. 7, 1942 2,343,351 Wedler Mar. 7, 1944 2,432,355 Truitt Dec. 9, 1947 2,450,948 Foster Oct. 12, 1948 2,574,200 Teague Nov. 6, 1951 2,649,623 Ingham, Ir. Aug. 25, 1953 FOREIGN PATENTS 513,354 Great Britain Oct. 10, 1939 

1. THE METHOD OF MAKING AN ELASTIC FABRIC WHICH COMPRISES, WEAVING A FABRIC OF TEXTILE YARNS HAVING A SMALL PERCENT OF HEAT-SHRINKABLE FILAMENTS SUFFICIENT TO SHRINK THE FABRIC A SUBSTANTIAL AMOUNT IN THE FABRIC IN THE DIRECTION IT IS TO STRETCH AND WHICH WILL SHRINK A SUBSTANTIAL AMOUNT IF FREE OF TENSION WHEN HEATED, HEATING THE FABRIC TO THE FILAMENT SHRINKAGE TEMPERATURE TO CONTRACT THE FABRIC AND HOLD IT CONTRACTED, COATING THE CONTRACTED FABRIC WITH RUBBER, CURING THE RUBBER, AND THEN BREAKING SAID FILAMENTS INTO SUFFICIENTLY SHORT LENGTHS TO RELEASE THE CONTRACTED FABRIC BY HEATING THE FABRIC TO THE FILAMENT SHRINKING TEMPERATURE AND WHILE AT THIS TEMPERATURE STRETCHING THE FABRIC TO CAUSE THE HEATED AND STRETCHED FILAMENTS TO BREAK UNDER THE COMBINED ACTION OF THE HEAT AND TENSION. 